The present invention relates to a method and an apparatus for managing an access path, and more particularly to a management of an access path in a multi-path system that accesses a storage device by means of plural access paths in a storage area network (SAN).
The popularization of the Internet and transformation of data into multimedia allow the storage capacity of a storage device used in enterprises or the like to increase. An SAN is established for an enormous quantity of data that rapidly increases. In the SAN, plural host computers and a large-capacity data storage device, in particular, a disk array are connected to each other through fiber channels or the like, to thereby realize data sharing and high-speed accessing.
Plural adaptors for connection to the SAN such as host bus adaptors (HBA) and channel adaptors (hereinafter referred to as “CHA”), and plural devices used for connection with fiber channel switches (hereinafter merely referred to as “switches”) and hubs exist between the host computers and the storage device. The respective devices are so connected as to ensure plural paths (hereinafter referred to as “physical paths”) assuming a defect. Under the circumstances, the connection relationships become remarkably complicated.
Also, in the data storage device such as the disk array, it is possible that a storage area that is made up of plural physical disks is shared to plural logical volumes (hereinafter referred to as “logical volumes”), and then released to a specific host computer. A path (hereinafter referred to as “access path”) for accessing to the logical volume from the host computer is set from options of the abovementioned plural physical paths. There has been used a technique by which plural access paths are set with respect to one logical volume, and one access path is switched over to another access path at the time of a defect to continue access operation, or the plural access paths are used at the same time to disperse an access load (hereinafter referred to as “multi-path management”).
For example, Japanese Published Unexamined Patent Application No. 2000-330924 discloses that the access load on the storage device is appropriately dispersed to the plural access paths in the technique of the above type.